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Second Skin Audio

Why 2+ ports??


k58.cross

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From my experience and understanding, port selection comes down to these factors:

Box Size

Tuning Frequency

Aesthetics

 

Every calculator tells me the following things:

2 smaller ports does not equal a bigger port.

The larger the port opening area, the longer the port has to be to tune lower.

 

Therefore, I question every time I see a 10+ inch diameter port sitting in a box in someone's mid-size sedan trunk. I also question when I see multiple smaller diameter ports of relatively short length.

Please prove me wrong (with technical proof), but it seems like alot of people don't really understand port math and are simply tossing stuff in based on their aesthetic wants. Do they not know it's screwing up their tuning?

 

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37 minutes ago, k58.cross said:

From my experience and understanding, port selection comes down to these factors:

Box Size

Tuning Frequency

Aesthetics

 

Every calculator tells me the following things:

2 smaller ports does not equal a bigger port.

The larger the port opening area, the longer the port has to be to tune lower.

 

Therefore, I question every time I see a 10+ inch diameter port sitting in a box in someone's mid-size sedan trunk. I also question when I see multiple smaller diameter ports of relatively short length.

Please prove me wrong (with technical proof), but it seems like alot of people don't really understand port math and are simply tossing stuff in based on their aesthetic wants. Do they not know it's screwing up their tuning?

 

If optimal performance is the goal, how much port area you need is mostly determined by box size, tuning frequency, and input power.  Input power is something many people forget about when determining their port size, often to the detriment of their system.  

Not everyone has optimal performance as their #1 priority, aesthetics may be more important to some people, so sacrificing a bit of performance to get the looks they want may be acceptable and there is nothing wrong with that.  To each their own.  Hopefully they fully understand what tradeoffs they are making, many people probably don't.  

When you say "it seems like alot of people don't really understand port math and are simply tossing stuff in based on their aesthetic wants" you are probably right if you are referring to car audio people in general.  There are a lot of people that DO know what they are doing though, and I would put most of the people on SMD in that category.  

If you want to see some technical data, I've done lots of my own research and experiments and published the data on this site.  Here are some examples:

 

 

"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

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4 hours ago, k58.cross said:

Perfect, thanks for the reply :) Yeah I didn't mean to come across snobby, I just meant it seems like a lot of the port choices I've been seeing don't make sense. Like check this out and let me know if there is method behind it:

https://www.ecoustics.com/electronics/forum/car-audio/288607.html

Sick builds there in your signature man.

 

What's your problem with that box exactly?  For example pay for those 4 round ports is wasteful compared to a zero cost for a slot port box but I'd like to know your reason.

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16 hours ago, Joe X said:

 

What's your problem with that box exactly?  For example pay for those 4 round ports is wasteful compared to a zero cost for a slot port box but I'd like to know your reason.

 

Actually, I went back and did the math and that one could work.

Just kind of eyeballing it from the pictures, it looks like the box would be about 5 cubes after displacement. If so, the calc tells me 4 aeroports of 4-inch diameter would have to be about 19 inches long each to tune overall to 35 Hz. If however, the net volume was only 3 cubes, they'd have to be over 33 inches long each. 

So yeah, I can see how I might be misjudging the boxes with multiple smaller ports. 

 

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When it comes to multiple ports, I try to keep it to 2 max. Unless the design just wont allow for 1 or 2 bigger ones, some kind of dimensional restraint. 

However on that box I think he could have easily gone with 1 or 2 slot ports.

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